Is it lower rod in 67 too?The pedal as such cannot be adjusted. The final position of the pedal is set by proper condition and adjustment of the clutch linkage. The linkage is designed to pull the pedal up to the stop at the top of its travel, and help pull it down when you disengage the clutch.
First is checking the condition of the nylon bushings on the clutch pedal, and the nylon insulators at each end of the assist spring. Then check the nylon bushings at each end of the upper rod, then the condition of the nylon ball bushings in each end of the equalizer. You should have a spring from the top equalizer arm to the firewall on late 66, and from the lower arm to the release lever on late 66. 65 and early 66 had only a single spring, from the release lever to the left shock tower (yeah, it's really long).
Once all this is intact, adjustment is simple. Remove the spring from the release lever. Adjust the linkage (the upper rod in 65, the lower rod in 66) until you have a 1/8" gap between the lower rod and the release lever. Install the spring. Done.